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A Night in The Pleiades

They are Rare and Will be Gone
Soon in Astronomical Time. These Seven
Sisters are a Great Destination for Your Celestial Observations.

The
Pleiades are a unique cluster of stars that burst into light 75 to 150 million
years ago and will disperse across the sky in a little more than 250 million
years. This is due to both the
gravitational effects of the Milky Way Galaxy and giant, molecular clouds in
the vicinity. That number of years is a
fairly brief event in cosmological time.
At a distance of a little less than 400 light years away from our Sun, it's
relatively close as a group. There is
some controversy about its actual
distance
but many sources cite 400 light years on average. It's estimated to be 4.5 light years wide at
its core radius and up to 50 light years wide at its outer edge. It's been determined that many stars in the
cluster are traveling at 40 kilometers a second with many moving in opposite
directions.

Above image by: NASA, ESA, AURA/Caltech, Palomar Observatory

Their
appearance and arrangement is similar to the Plough (Big Dipper) but on a much
smaller and dimmer scale. Dark-night
viewing is the best way to see The Pleiades and binoculars or a reduced
magnification on a telescope will allow you to see the full cluster. A large aperture with its ability to capture
light can help as well.

Many
of the stars appear hazy and surrounded by complex, blue filaments of light. This is due to dust particles in a large
nebula that cuts across the cluster. According
to the Kitt Peak Observatory a second cloud is also evident creating a unique
combination of interstellar events.

Sometimes
referred to as the Seven Sisters, six stars are apparent with the naked eye,
but any magnification will bring the seventh and others into view. In fact, it's estimated more than 1,000 stars
reside in the cluster although there are some estimates that put the number as
high as 3,000. It's also known as M45,
Messier 45 and "Subaru" in Japanese.

Map of M45. Image by: NASA, ESA and AURA/Caltech

How To Find the Pleiades

The
constellation Orion is a good place to start if you're having trouble locating The Pleiades. Simply imagine a line through Orion's belt
and look to your right. You'll notice a
V-shaped arrangement of stars. This is
the head of Taurus the Bull. The
brightest star in the "V" is Aldebaran. To the right of Aldebaran you'll notice a
small dipper configuration - that's The Pleiades.

Much
like Orion, The Pleiades are considered a winter event in the Northern
hemisphere fading below the horizon in late April and re-emerging in
September. November is the prime month
with The Pleiades high in the sky.

Once
you've located the Pleiades and spent some time studying this unique cluster - you'll
find it very easily and turn to its shimmering, blue light often.